The present invention relates to thermal insulation products, and more particularly to fluid conduits or containers thermal insulation envelops.
These products, usually in the form of sleeves or slabs, are customarily made of foamed polymeric material, mostly polyurethane (hereinafter for short "PU"), rubber and other polymers, both in elastic and in rigid forms. These materials are widely used due to their increased impact resistance and water protection capacity..
On the other hand, these materials are inferior in other respects: low temperature resistivity and lost of elasticity under relatively low temperature (about 90.degree. C).
Mineral and glass wool (hereinafter for short "MW") have long been used as thermal insulators. While these materials have excellent insulating characteristics and high thermal resistivity, they posses low mechanical strength and low impact resistance, and are pervious to water. After prolonged use, articles made of MW may loose their shape and, moreover microscopic fibers are released, carried in the ambient air and may cause damage to the human health when penetrating the breathing system or eyes.
It is therefore the general object of the present invention to overcome the above detailed deficiencies, by providing a hybrid insulation structure that will combine the higher heat resistance of inorganic insulators such as MW, with the increased impact resistance and water protection of the polymer based materials.
It is a further object of the invention to form insulator envelops of an inner MW layer and an outer protective PU layer.
It is a still further object of the invention to achieve the optimal ratio of the inorganic and polymeric layers thicknesses.